Abscesses are infected walled-off fluid collections of pus and bacteria, and represent a ubiquitous global healthcare problem. They are common sequelae of surgery, infections or disease, and can affect any part of the body. Current standard of care includes hospitalization, antibiotics and drainage of the abscess with a catheter. The bacteria in puss are susceptible to both thermal and mechanical damage. High Intensity Focused Ultrasound (HIFU) can generate localized heating and cavitation, and is a potential noninvasive means to treat abscesses by exploiting one or both mechanisms. The significance of this proposal is that noninvasive treatment of reachable abscesses using ultrasound therapy under ultrasound guidance is better for the patient because it is noninvasive, allows treatment of small abscesses, has less procedural pain, requires no catheter management, there is no potential tract for new infections, and no need for CT/fluoro imaging radiation.